String.util 		不要重复造轮子

spring-core: 
org.springframework.util.StringUtils 

apache commons-lang 2.x 
org.apache.commons.lang.StringUtils 
apache commons-lang 3.x 
org.apache.commons.lang3.StringUtils 

guava: 
com.google.common.base 
Strings, CharMatcher, Ascii, Joiner, Splitter, Utf8, CaseFormat ..... 